Diffusion-adsorption kinetics of anionic surfactants at a liquid-liquid interface: An analytical and experimental study
Hamilton K. Kalam S. Hassanzadeh H.
1 September 2025American Institute of Physics
Physics of Fluids
2025#37Issue 9
We present a new dynamic interfacial adsorption model for estimating the diffusion and adsorption kinetics of the anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) at an n-decane-water interface. The migration of surfactant molecules to the interface progressively reduces the dynamic interfacial tension. From these data, equilibrium fitting parameters are estimated using adsorption models, including the Langmuir, Frumkin, van der Waals, and Volmer models. The experimental data are further analyzed using the proposed analytical model, which calculates the surface concentration as a function of diffusivity and adsorption rate. This time-dependent surface concentration is then related to interfacial tension by the Frumkin equation of state. Consequently, the apparent diffusion coefficient and adsorption rate constant are estimated from the best fit of the model to the experimentally measured data. The results show that SDS exhibits higher initial diffusivity and faster adsorption rates. In contrast, SDBS achieves a lower interfacial tension at equilibrium despite its lower diffusivity and slower adsorption rates. The comparative observations span concentrations from dilute to near the critical micelle concentration at 25 °C.
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Department of Chemical & Petroleum Engineering, Schulich School of Engineering, University of Calgary, Calgary, T2N 1N4, AB, Canada
School of Mining and Geosciences, Nazarbayev University, Astana, 010000, Kazakhstan
Department of Chemical & Petroleum Engineering
School of Mining and Geosciences
10 лет помогаем публиковать статьи Международный издатель
Книга Публикация научной статьи Волощук 2026 Book Publication of a scientific article 2026